DynamicObject.TryBinaryOperation 方法

定义

命名空间:

System.Dynamic

程序集:

System.Linq.Expressions.dll

Source:

DynamicObject.cs

提供二元运算的实现。 从 DynamicObject 类派生的类可以重写此方法，以便为诸如加法和乘法这样的运算指定动态行为。

public:
 virtual bool TryBinaryOperation(System::Dynamic::BinaryOperationBinder ^ binder, System::Object ^ arg, [Runtime::InteropServices::Out] System::Object ^ % result);

public virtual bool TryBinaryOperation (System.Dynamic.BinaryOperationBinder binder, object arg, out object? result);

abstract member TryBinaryOperation : System.Dynamic.BinaryOperationBinder * obj * obj -> bool
override this.TryBinaryOperation : System.Dynamic.BinaryOperationBinder * obj * obj -> bool

Public Overridable Function TryBinaryOperation (binder As BinaryOperationBinder, arg As Object, ByRef result As Object) As Boolean

参数

binder

BinaryOperationBinder

提供有关二元运算的信息。 属性 binder.Operation 返回 对象 ExpressionType 。 例如，对于 sum = first + second 从 类派生的 DynamicObject 和 second 的 语句first，binder.Operation返回 ExpressionType.Add。

arg

Object

二元运算的右操作数。 例如，对于 sum = first + second 从 类派生的 DynamicObject 和 second 的 语句first，arg等于 second。

result

Object

二元运算的结果。

返回

Boolean

如果操作成功，则为 true；否则为 false。 如果此方法返回 false，则该语言的运行时联编程序将决定行为。 （大多数情况下，将引发语言特定的运行时异常。）

示例

假设需要一个数据结构来存储数字的文本和数字表示形式，并且想要定义基本数学运算，例如此类数据的加法和减法。

下面的代码示例演示 DynamicNumber 派生自 类的 DynamicObject 类。 DynamicNumber 重写 方法以 TryBinaryOperation 启用数学运算。 它还重写 TrySetMember 和 TryGetMember 方法，以启用对元素的访问。

在此示例中，仅支持加法和减法运算。 如果尝试编写类似 的 resultNumber = firstNumber*secondNumber语句，则会引发运行时异常。

// Add using System.Linq.Expressions;
// to the beginning of the file.

// The class derived from DynamicObject.
public class DynamicNumber : DynamicObject
{
    // The inner dictionary to store field names and values.
    Dictionary<string, object> dictionary
        = new Dictionary<string, object>();

    // Get the property value.
    public override bool TryGetMember(
        GetMemberBinder binder, out object result)
    {
        return dictionary.TryGetValue(binder.Name, out result);
    }

    // Set the property value.
    public override bool TrySetMember(
        SetMemberBinder binder, object value)
    {
        dictionary[binder.Name] = value;
        return true;
    }

    // Perform the binary operation.
    public override bool TryBinaryOperation(
        BinaryOperationBinder binder, object arg, out object result)
    {
        // The Textual property contains the textual representaion
        // of two numbers, in addition to the name
        // of the binary operation.
        string resultTextual =
            dictionary["Textual"].ToString() + " "
            + binder.Operation + " " +
            ((DynamicNumber)arg).dictionary["Textual"].ToString();

        int resultNumeric;

        // Checking what type of operation is being performed.
        switch (binder.Operation)
        {
            // Proccessing mathematical addition (a + b).
            case ExpressionType.Add:
                resultNumeric =
                    (int)dictionary["Numeric"] +
                    (int)((DynamicNumber)arg).dictionary["Numeric"];
                break;

            // Processing mathematical substraction (a - b).
            case ExpressionType.Subtract:
                resultNumeric =
                    (int)dictionary["Numeric"] -
                    (int)((DynamicNumber)arg).dictionary["Numeric"];
                break;

            // In case of any other binary operation,
            // print out the type of operation and return false,
            // which means that the language should determine
            // what to do.
            // (Usually the language just throws an exception.)
            default:
                Console.WriteLine(
                    binder.Operation +
                    ": This binary operation is not implemented");
                result = null;
                return false;
        }

        dynamic finalResult = new DynamicNumber();
        finalResult.Textual = resultTextual;
        finalResult.Numeric = resultNumeric;
        result = finalResult;
        return true;
    }
}

class Program
{
    static void Test(string[] args)
    {
        // Creating the first dynamic number.
        dynamic firstNumber = new DynamicNumber();

        // Creating properties and setting their values
        // for the first dynamic number.
        // The TrySetMember method is called.
        firstNumber.Textual = "One";
        firstNumber.Numeric = 1;

        // Printing out properties. The TryGetMember method is called.
        Console.WriteLine(
            firstNumber.Textual + " " + firstNumber.Numeric);

        // Creating the second dynamic number.
        dynamic secondNumber = new DynamicNumber();
        secondNumber.Textual = "Two";
        secondNumber.Numeric = 2;
        Console.WriteLine(
            secondNumber.Textual + " " + secondNumber.Numeric);

        dynamic resultNumber = new DynamicNumber();

        // Adding two numbers. The TryBinaryOperation is called.
        resultNumber = firstNumber + secondNumber;

        Console.WriteLine(
            resultNumber.Textual + " " + resultNumber.Numeric);

        // Subtracting two numbers. TryBinaryOperation is called.
        resultNumber = firstNumber - secondNumber;

        Console.WriteLine(
            resultNumber.Textual + " " + resultNumber.Numeric);

        // The following statement produces a run-time exception
        // because the multiplication operation is not implemented.
        // resultNumber = firstNumber * secondNumber;
    }
}

// This code example produces the following output:

// One 1
// Two 2
// One Add Two 3
// One Subtract Two -1

' Add Imports System.Linq.Expressions
' to the beginning of the file.
' The class derived from DynamicObject.
Public Class DynamicNumber
    Inherits DynamicObject

    ' The inner dictionary to store field names and values.
    Dim dictionary As New Dictionary(Of String, Object)

    ' Get the property value.
    Public Overrides Function TryGetMember(
        ByVal binder As System.Dynamic.GetMemberBinder,
        ByRef result As Object) As Boolean

        Return dictionary.TryGetValue(binder.Name, result)

    End Function

    ' Set the property value.
    Public Overrides Function TrySetMember(
        ByVal binder As System.Dynamic.SetMemberBinder,
        ByVal value As Object) As Boolean

        dictionary(binder.Name) = value
        Return True

    End Function

    ' Perform the binary operation. 
    Public Overrides Function TryBinaryOperation(
        ByVal binder As System.Dynamic.BinaryOperationBinder,
        ByVal arg As Object, ByRef result As Object) As Boolean

        ' The Textual property contains the textual representaion 
        ' of two numbers, in addition to the name of the binary operation.
        Dim resultTextual As String =
            dictionary("Textual") & " " &
            binder.Operation.ToString() & " " &
        CType(arg, DynamicNumber).dictionary("Textual")

        Dim resultNumeric As Integer

        ' Checking what type of operation is being performed.
        Select Case binder.Operation
            ' Proccessing mathematical addition (a + b).
            Case ExpressionType.Add
                resultNumeric =
                CInt(dictionary("Numeric")) +
                CInt((CType(arg, DynamicNumber)).dictionary("Numeric"))

                ' Processing mathematical substraction (a - b).
            Case ExpressionType.Subtract
                resultNumeric =
                CInt(dictionary("Numeric")) -
                CInt((CType(arg, DynamicNumber)).dictionary("Numeric"))

            Case Else
                ' In case of any other binary operation,
                ' print out the type of operation and return false,
                ' which means that the language should determine 
                ' what to do.
                ' (Usually the language just throws an exception.)
                Console.WriteLine(
                    binder.Operation.ToString() &
                    ": This binary operation is not implemented")
                result = Nothing
                Return False
        End Select

        Dim finalResult As Object = New DynamicNumber()
        finalResult.Textual = resultTextual
        finalResult.Numeric = resultNumeric
        result = finalResult
        Return True
    End Function
End Class

Sub Test()
    ' Creating the first dynamic number.
    Dim firstNumber As Object = New DynamicNumber()

    ' Creating properties and setting their values
    ' for the first dynamic number. 
    ' The TrySetMember method is called.
    firstNumber.Textual = "One"
    firstNumber.Numeric = 1

    ' Printing out properties. The TryGetMember method is called.
    Console.WriteLine(
        firstNumber.Textual & " " & firstNumber.Numeric)

    ' Creating the second dynamic number.
    Dim secondNumber As Object = New DynamicNumber()
    secondNumber.Textual = "Two"
    secondNumber.Numeric = 2
    Console.WriteLine(
        secondNumber.Textual & " " & secondNumber.Numeric)

    Dim resultNumber As Object = New DynamicNumber()

    ' Adding two numbers. TryBinaryOperation is called.
    resultNumber = firstNumber + secondNumber
    Console.WriteLine(
        resultNumber.Textual & " " & resultNumber.Numeric)

    ' Subtracting two numbers. TryBinaryOperation is called.
    resultNumber = firstNumber - secondNumber
    Console.WriteLine(
        resultNumber.Textual & " " & resultNumber.Numeric)

    ' The following statement produces a run-time exception
    ' because the multiplication operation is not implemented.
    ' resultNumber = firstNumber * secondNumber
End Sub

' This code example produces the following output:

' One 1
' Two 2
' One Add Two 3
' One Subtract Two -1

注解

派生自 类的 DynamicObject 类可以重写此方法，以指定应如何对动态对象执行二进制操作。 当方法未重写时，语言的运行时绑定器将确定行为。 （大多数情况下，将引发语言特定的运行时异常。）

当具有二进制运算（例如加法或乘法）时，将调用此方法。 例如，如果TryBinaryOperation重写了 方法，则会自动为 或 multiply = first*second等sum = first + second语句调用该方法，其中first派生自 DynamicObject 类。

可以使用 参数的 属性binder获取有关二进制操作Operation类型的信息。

如果动态对象仅在 C# 和 Visual Basic 中使用，则 binder.Operation 属性可以从枚举中 ExpressionType 具有以下值之一。 但是，在其他语言（如 IronPython 或 IronRuby）中，可以具有其他值。

“值”	说明	C#	Visual Basic
Add	不进行溢出检查的加法运算，用于数字操作数。	a + b	a + b
AddAssign	不进行溢出检查的加法复合赋值运算，用于数字操作数。	a += b	不支持。
And	按位 AND 运算。	a & b	a And b
AndAssign	按位 AND 复合赋值运算。	a &= b	不支持。
Divide	算术除法运算。	a / b	a / b
DivideAssign	算术除法复合赋值运算。	a /= b	不支持。
ExclusiveOr	按位 XOR 运算。	a ^ b	a Xor b
ExclusiveOrAssign	按位 XOR 复合赋值运算。	a ^= b	不支持。
GreaterThan	“大于”比较。	a > b	a > b
GreaterThanOrEqual	“大于或等于”比较。	a >= b	不支持。
LeftShift	按位左移运算。	a << b	a << b
LeftShiftAssign	按位左移复合赋值运算。	a <<= b	不支持。
LessThan	“小于”比较。	a < b	a < b
LessThanOrEqual	“小于或等于”比较。	a <= b	不支持。
Modulo	算术余数运算。	a % b	a Mod b
ModuloAssign	算术余数复合赋值运算。	a %= b	不支持。
Multiply	对于数值操作数，无需溢出检查的乘法运算。	a * b	a * b
MultiplyAssign	对于数值操作数，无需溢出检查的乘法复合赋值运算。	a *= b	不支持。
NotEqual	不相等比较。	a != b	a <> b
Or	按位运算或逻辑 OR 运算。	a &#124; b	a Or b
OrAssign	按位或逻辑 OR 复合赋值。	a &#124;= b	不支持。
Power	将数字提高到幂的数学运算。	不支持。	a ^ b
RightShift	按位右移运算。	a >> b	a >> b
RightShiftAssign	按位右移复合赋值运算。	a >>= b	不支持。
Subtract	不进行溢出检查的减法运算，用于数字操作数。	a - b	a - b
SubtractAssign	对于数值操作数，无需溢出检查的减法复合赋值运算。	a -= b	不支持。

备注

若要在 C# 中实现 OrElse (a || b) 和 AndAlso (a && b) 操作，可能需要同时 TryUnaryOperation 实现 方法和 TryBinaryOperation 方法。

该 OrElse 操作由一元 IsTrue 运算和二进制 Or 运算组成。 Or仅当操作的结果为 false时，IsTrue才会执行该操作。

该 AndAlso 操作由一元 IsFalse 运算和二进制 And 运算组成。 And仅当操作的结果为 false时，IsFalse才会执行该操作。